The 2011-12 winter will long be remembered for
warmth and lack of snow, and in some locations near record setting
snowfall departures. The winter was very mild and the November
through March timeframe consistently had well above normal
temperatures. Cold blasts were few and short lived and the snow that
did fall quickly melted. Many areas were green for much of the
winter as widespread synoptic snows were also few and light.

Snowfall

Much of the country east of the Rockies this winter fell short of
their seasonal snowfall normal. This was true across the Eastern
Great Lakes region as well, with many areas less than 50 percent of
their typical winter snowfall totals.

The lake effect season again was off to a slow start. The first
event occurred in mid November, and only two events through
December.

For the winter season, there were eight lake effect "events" which
is two fewer than average. The most impressive lake effect event
occurred at the end of January when a localized area south and east
of Lake Ontario received impressive two-feet plus of snow in a
relatively short period of time. For our major metropolitan areas,
Rochester had a significant lake effect snowstorm of a foot, which
was its first in several years of this magnitude. Fortunately it
fell at the most opportune time, the weekend, with minimal impact on
the city.

Heaviest snowfall was over Oswego and the Tug Hill where 100+ inches
of snow fell, mainly on frequent light to moderate lake effect snow
events. Across Western New York, a few higher elevations of the
Chautauqua ridge and hills of Wyoming County also reached the 100
inch mark with all other locations well below normal.

Seasonal snowfall at the two primary climate locations of Buffalo
and Rochester were well below normal. Lack of snow combined with the
above normal warmth greatly limited the duration of snow through the
winter with the longest stretch of one inch or more of snow on the
ground in Buffalo being 5 days, and 6 days for Rochester.

Temperatures

Temperatures in November through March remained 5.0 F or greater all
five months for both Buffalo and Rochester. This was the warmest
November through March timeframe in the recorded history for both
Buffalo and Rochester. With the persistent warmth the amount of days
the temperature remained below freezing was abnormally low with only
17 such days in Buffalo and 19 days in Rochester; and of these days,
only 4 were found to be consecutive. The warmest March in history
closed out the epic winter season.

Hemispheric Pattern

The Winter of 2011-12 proved to be historically mild and relatively
snow free across Western and North Central New York. Some of the
main contributors to this were an abnormally deep and persistent
Icelandic Low and a strong Azores High that encouraged a fast zonal
upper level flow across Eastern North America and the North
Atlantic. This stronger than normal zonal flow kept Arctic air
bottled up over the high latitudes while flooding much of the lower
48 with mild Pacific air. Normally, the jet stream over North
America exhibits a higher amplitude. The corresponding meridional
component to the jet stream this past winter was very weak.

While Icelandic Low's are quite common during the winter months,
they periodically give way to persistent areas of high pressure.
These high pressure systems are associated with ridging that extends
from the North Atlantic poleward across Greenland. These 'Greenland
blocks' can persist for weeks at a time and act as a barrier to the
upper level flow exiting North America. The blocking pattern enables
closed lows to develop over Eastern Canada, which in turn encourages
intrusions of Arctic air over the Great Lakes region. This is often
referred to as the negative phase of the North Atlantic Oscillation
(NAO).

During this past winter, a Greenland block was virtually
non-existent as low pressure was very persistent in the vicinity of
Iceland. In fact, the strength and persistence of the resulting
positive NAO had not been witnessed since the winter of 1999-2000
when we experienced one of our top 30 'warmest' winters (out of more
than 140 winters). That particular winter was also one that featured
relatively little snow.

While our winters are often correlated to what is happening over the
Equatorial Pacific (El Nino / La Nina), this is past winter was just
more evidence that the Great Lakes region is heavily influenced by
the strength and phase of the North Atlantic Oscillation.

While the month was tranquil on average, there were a few notable
weather events in Western New York in November. On the 14th there
were two EF2 tornadoes in the Chautauqua County towns of Westfield
and Fredonia. These are the first two tornadoes on record in Western
New York in the
month of November going back at least 50 years. There were also two
lake effect snow events, one November 11th and another on the 17th (Ayrshire)
across Ski Country and the Southern Tier well south of Buffalo. In
both cases temperatures quickly warmed to melt the snow a day or two
later.

December 2011

December 2011 will be long remembered for the incredible lack of
winter weather. Temperatures were well above average with only a
handful of days cold enough to support lake effect snow. There was
practically no snow for the month, and the ground remained green for
many areas for the month. This was a continuation of similar
conditions in November, making this fall and early winter through
December 31st one of the least snowy starts to winter on record.
Snowfall was woefully low throughout Western and Central New York,
even in the normally snowy lake effect snowbelt locations of the
Southern Tier.

January 2012

This was the first month that actually resembled winter in terms of
snowfall. Temporary surges of arctic air did bring more significant
lake effect snows to the Southern Tier and to the ski resorts. West
and northwest flow brought several lake effect snow events to areas
south and east of Lake Ontario with many areas having their greatest
monthly snowfall totals this month. There were three named lake
effect events this month. Unfortunately, a significant warm up late
in the month helped to erode a lot of the snowpack.

February 2012

Winter continued its sparse appearance this month. Several lake
effect events occurred in February, including one on a northwest
flow in mid February that brought over a foot of snow to the
Rochester metropolitan area, the largest snowfall event in Rochester
for the year. Greatest snow totals for the month were found south of
the Lake Ontario shoreline and the mid month lake effect event aided
in Rochester finishing with above normal snowfall for the month.
Another late month lake effect snow event with upstream connections
to Georgian Bay and Lake Huron brought a foot of snow to the Ski
country regions of Western New York.

March 2012

March will be remembered for the incredible and long duration warmth
through the month. Temperatures well above normal were not conducive
for lake effect snow, and synoptic storms were few and minor. Areas
outside the eastern Lake Ontario region finished with less than a
half a foot of snow, which is well below normal while parts of the
Tug Hill were able to reach the one foot mark.

April 2012

It looked like most of the region would finish April with no
accumulating snow, however a late season storm moved across the
eastern Great Lakes with snow falling across the region the third
week of the month. This was an elevation driven event with up to 6
inches falling on the Tug Hill, while parts of the southern tier
reached over 12 inches of snow. Snow even accumulated at lower
elevations of metro Buffalo, Rochester and Watertown. However the
strong late April sun angle quickly melted the snow.